Iterative Block Decision Feedback Equalization for MIMO Underwater Acoustic Communications

A new receiver design using iterative block decision-feedback equalizer (BDFE) is proposed for high data rate single-carrier multiple-input, multiple-output (MIMO) underwater acoustic (UWA) communications. The adoption of BDFE enables a sequence-based log-likelihood ratio (LLR) calculation during iterative equalization, thus leading to better performance and faster convergence than existing low-complexity iterative equalization methods using symbol-based LLR evaluation. The proposed BDFE method is applied to overlapped blocks to reduce performance degradation at the tail of each block. The block size is flexibly selected depending on the practical channel condition. The proposed receiver scheme has been tested by extensive experimental data and proved to be robust to different transmission environments with consistently good detection performance. Data from collected during the SPACE08 experiment near Martha's Vineyard and the GOMEX08 experiment at the Gulf of Mexico, are both presented here.